2+ Feet of new snow on Tamarack Pk, soft windslab

We skinned up from the Tamarack parking lot to the summit with some wind and blowing snow.  Near the top, on the ridge overlooking Hourglass, I stepped out and experienced a sudden collapse.  As the picture shows, the snow was partly over a small tree creating an air pocket, but there was also a weak wind slab. No propagation.  We skied off the right side of HG without any wind slab but did hit some rocks buried by the new snow.  On our climb out of HG one member of our party thought she heard/felt a whumpf. We then skied Proletariat without noting any instabilities.